This Mentored Patient-Oriented Research Career Development Award (K23) is a five year training program that supports the candidate to become an expert in the social neuroscience of interpersonal reactivity in Borderline Personality Disorder (BPD). BPD has not received research attention and widespread clinical focus commensurate with the suffering and mortality it causes. Between 600 and 1.4 million adults in the United States meet diagnostic criteria for BPD. The suicide rate for BPD individuals is high and it is the psychiatric diagnosis associated with the highest rate of non-suicidal self-injury such as self-cutting and burning. Interpersonal reactivity in BPD is associated with non suicidal self-injury, suicidality, high rates of health care utilization, and intense, chronic emotional pain. This training and research plan incorporates the study of three levels of analysis to investigate interpersonal reactivity in BPD: the behavioral, psychophysiological, and neural. Consistent with a translational research approach, social neuroscience uses the tools of modern neuroscience (such as functional Magnetic Resonance Imaging [fMRI]) to link social processes with the neural circuits and structures that subserve them. Eventually, this approach and these methods can be used to identify the mechanisms that underlie BPD and other psychiatric disorders, and to inform and evaluate prevention and therapeutic interventions. Education and Expert Mentorship for the candidate will be provided by Dr. Barbara Stanley (BPD research), Dr. J. John Mann (neurobiology of psychiatric disorders and suicide), Dr. Joy Hirsch (fMRI research), Dr. Kevin Ochsner (fMRI methods to study emotion and social cognition), Dr. Paul Pilkonis (measurement and modeling of interpersonal behavior in personality disorders), and Dr. Tor Wager (statistics and methods in fMRI). Research Project: Two groups of subjects will be compared: a) BPD participants and b) healthy controls. The Primary Aims are 1). To utilize a translational, social neuroscience approach to identify indicators of interpersonal reactivity in BPD at behavioral, psychophysiological, and neural levels. 2) To model the relationship between automatic and controlled indicators of interpersonal reactivity and the features of BPD.